'\" et
.TH FWIDE "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
fwide
\(em set stream orientation
.SH SYNOPSIS
.LP
.nf
#include <stdio.h>
#include <wchar.h>
.P
int fwide(FILE *\fIstream\fP, int \fImode\fP);
.fi
.SH DESCRIPTION
The functionality described on this reference page is aligned with the
ISO\ C standard. Any conflict between the requirements described here and the
ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard.
.P
The
\fIfwide\fR()
function shall determine the orientation of the stream pointed to by
.IR stream .
If
.IR mode
is greater than zero, the function first attempts to make the stream
wide-oriented. If
.IR mode
is less than zero, the function first attempts to make the stream
byte-oriented. Otherwise,
.IR mode
is zero and the function does not alter the orientation of the stream.
.P
If the orientation of the stream has already been determined,
\fIfwide\fR()
shall not change it.
.P
The
\fIfwide\fR()
function shall not change the setting of
.IR errno
if successful.
.P
Since no return value is reserved to indicate an error, an
application wishing to check for error situations should set
.IR errno
to 0, then call
\fIfwide\fR(),
then check
.IR errno ,
and if it is non-zero, assume an error has occurred.
.SH "RETURN VALUE"
The
\fIfwide\fR()
function shall return a value greater than zero if, after the call, the
stream has wide-orientation, a value less than zero if the stream has
byte-orientation, or zero if the stream has no orientation.
.SH ERRORS
The
\fIfwide\fR()
function may fail if:
.TP
.BR EBADF
The
.IR stream
argument is not a valid stream.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
A call to
\fIfwide\fR()
with
.IR mode
set to zero can be used to determine the current orientation of a
stream.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<stdio.h>\fP",
.IR "\fB<wchar.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
